Quartz Substrates Research Articles

Design of a binary programmable transmitarray based on phase change material for beam steering applications in D-band

This paper introduces the design of a reconfigurable transmitarray operating within the D-band frequency range (110–170 GHz). The transmitarray unit cell is composed of three metal layers and two quartz dielectric substrates. It achieves a 1-bit phase shift resolution through the alternating states of two innovative switches integrated into the active transmitting patch of the unit cell. To address the challenge of miniaturization in the D-band, compact switches compatible with the proposed unit cell dimensions are introduced. These switches are constructed using phase change materials (PCM) that change between amorphous and crystalline states when exposed to heat. The paper includes a full-wave simulation of the unit cell, demonstrating an insertion loss below 1.5 dB across a wide frequency band of 27%. Additionally, a 10 ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes $$\\end{document} 10 elements transmitarray is synthesized using a numerical tool and its theoretical results are compared to full-wave electromagnetic simulations for validation purposes. The results indicate that by incorporating the proposed switches into the unit cell, the transmitarray achieves promising reconfiguration capabilities within the D-band. Moreover, the paper presents the architecture of a command line designed to bias the PCM switches. Notably, this command line represents a novel approach, as it enables individual biasing of each PCM switch using direct current (DC). The influence of these command lines on the transmitarray’s performance is thoroughly investigated. Although there is a compromise in the 1-dB gain bandwidth, the overall behavior of the transmitarray remains encouraging.

INVESTIGATION OF PHOTOVOLTAIC POTENTIALS OF A SILVER IMPLANTED DIAMOND-LIKE CARBON THIN FILM

This paper investigated the optical response of silver implanted carbon-based thin films (deposited on quartz substrates) due to varying fluence of energetic Ag ions in the range 2.5 - 3.4 x 1016 ions/cm2. Raman spectroscopy was used to observe the microstructural specifics of the Ag:a-C composites. Atomic force microscopy (AFM) revealed significant increase in particle grain size and surface roughness of the films at varying fluences. Optical absorption spectra showed that the Surface Plasmon Resonance (SPR) of pristine Ag occurs at visible wavelength of about 428 nm but exhibited a blue shifting (~ 32 nm) in the implanted films. The blue shift in plasmonic wavelength occurs due to the fluence-induced increase in grain size and density of the Ag particles as confirmed by AFM. Optical band gap energy () and Urbach parameter () of the pristine carbon film increased, with fluence, from 2.89 eV to 1.60 eV and 3.60 eV to 4.22 eV respectively. The observed optically active parameters strongly indicate that the composites would make good candidates for photon retention towards the enhancement of solar cells’ efficiency.

Crystal growth, optical, photoluminescence and magnetic properties of sol-gel GdFeO3 thin film

GdFeO3 (GFO) orthoferrite is a perovskite structured material with rich physical properties. In this work, crystal growth, electronic, optical, photoluminescence (PL) and magnetic properties of sol-gel synthesized GFO thin films onto quartz substrate were investigated. The films were annealed at various temperature 650–900 °C. XRD results showed transformation from an amorphous to nanocrystalline GFO and GdO secondary phase with rise of annealing temperature from 650 to 700 °C. Single phase GFO was observed in films annealed above 700 °C. Crystallite size of the films gradually increased from 10.5 to 89.9 nm for films annealed from 700 to 900 °C, respectively. The surface morphology changed from porous microstructure consisted of tiny particulates in film annealed at 700 °C into enlarged particles and clear polycrystalline structure in films annealed above 700 °C. From XPS spectra analysis, both Fe and Gd ions existed in a 3+ valence state. The films demonstrated optical band gap ranged between 2.8 and 3 eV. The PL spectra obtained using a 300 nm excitation wavelength consisted of four emission peaks. The near band edge emission of the films varied between 449.9 and 455.1 nm. The films showed weak ferromagnetic behavior with magnetization ranging from 24 to 49 emu/cm3.

Temperature control of atomic gas chamber using a nonmagnetic heating chip fabricated on quartz substrate

Nonmagnetic electrical heating and temperature sensing chip fabricated on quartz substrate is developed, and a high-precision digital temperature control system is designed based on this chip. The heating resistance and temperature sensing resistance are prepared by depositing two layers of Ti/Pt alloy electrodes on quartz substrate through magnetic field cancellation design. The temperature coefficient of fabricated Ti/Pt temperature sensing resistance is +0.197%/℃. The simulation results show that the residual magnetic field generated by the heating current in the atomic gas chamber closely adjacent to the chip is less than 0.1 nT. Temperature control in the range of 100~150 ℃ is realized, and the temperature stability is about 0.02 ℃. Due to the high light transmittance of quartz glass, this heating chip has significant advantages for optical integration and miniaturization of atomic magnetometers.

Получение и исследование плёнок нитрида алюминия

Aluminum nitride films were produced on substrates of quartz, glass, aluminum and steel by reactive RF magnetron sputtering and ion–beam processing. The thickness of aluminum nitride coatings decreases with increasing current of ion-beam processing from 1700 to 650 Å. According to the energy dispersive analysis of films on steel and aluminum substrates, the nitrogen concentration increases with increasing current of ion-beam treatment. The X-ray phase analysis of the resulting films has shown that aluminum nitride films are X-ray amorphous. Aluminum nitride films are highly transparent. An increase in the refractive index of the films from 1.74 to 1.80 (for wavelength λ = 586 nm) and band gap from 5.32 to 5.61 eV with increasing current of ion-beam treatment was revealed. The band gap and refractive index values correlate satisfactorily with the literature data for aluminum nitride. Electron and atomic force microscopy has shown that aluminum nitride films are homogeneous and smooth. Roughness decreases with the introduction of ion-beam processing. It is found that the microhardness of the films deposited on aluminum substrates has increased by a factor of 1.5, and a 2.2 fold increase has been observed for the microhardness of the films deposited on steel substrates t. The maximum increase in microhardness is observed at the current of ion-beam processing of 40 mA.

16-channel snapshot multispectral imaging based on integrated Fabry Perot microcavity array

<sec>By designing and fabricating a narrow-band Fabry-Perot multi-beam interference spectroscopic microcavity array, and integrating it with a visible light detector focal plane array, we demonstrate a small compact multispectral imaging detector. The micro-cavity filter array with 4×4 basic repeating units and a total of 2048×2048 pixels is obtained on a quartz substrate by the four-fractal combination lithograph-etching process. Then the micro miniatured multispectral imaging detector is formed by fitting with the detector chip. The depth and precision of the etching will determine the distribution and offset of the central wavelength of the narrowband spectral channel respectively. The results show that the etching rate of reactive ion is (3.6 ± 0.2) Å/s, and the process is stable and controllable. Due to the different etching depths, the basic repeating unit forms 16 different levels of steps, and the process achieves the design expectation well.</sec><sec>The results are obtained as follows: the response spectrum peak of the microcavity array sample varies from 520 to 680 nm, the free spectrum range is 160 nm, the full width at the half-peak is less than 10 nm, the transmittance is about 70%, the relative half-width of the transmittance peak at 590 nm is 1.19%, and the waveform coefficient is 2.78. A 16-channel multispectral camera is constructed by using the optical micro-precision assembly device to realize the precise alignment and the fitting of the micro-cavity filter array and the image sensor. Xenon lamp and monochromator are used as tunable wavelength monochromatic cooperative light source to detect the effect of 16-channel snapshot multispectral imaging on a pixel scale. The results show that the multispectral imaging detector has 16 different narrow-band response spectra. The characteristic spectrum of the target can be clearly distinguished by spectral channel.</sec><sec>When imaging the target with known spectral characteristics, for a certain frame of multi-spectral image, selecting a suitable spectral channel can eliminate the background in the field of view through image subtraction and improve the contrast of the target. In the dark room condition, we take the LED light source with center wavelength varying in a range between 528 and 589 nm as the target (the wavelength coincides with the working wavelength of the spectral channel), and effectively suppress the background through the spectral differential intensity subtraction, which can improve the accuracy and sensitivity of the target capture. The 16-channel snapshot multi-spectral imaging detector based on integrated Fabry-Perot microcavity array has the advantages of small size, high integration and strong environmental adaptability, and is expected to play a role in realizing the real-time detection of weak moving targets, auxiliary diagnosis of skin surface observation, and high dynamic range imaging of target observation under backlight conditions.</sec>

High photoinduced birefringence in thermally treated layers of the azopolymer PAZO with significantly changed absorbance spectrum

In this experimental work we present the effect of thermal treatment of azopolymer thin films on their absorbance spectra and how that influences the photoinduced birefringence of the azopolymer. The azopolymer we use – PAZO (poly[1-[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2ethanediyl, sodium salt]) is commonly investigated material for polarization holography because it is easily accessible and has well pronounced photoanisotropic properties. In a recent study it was discovered that its absorbance spectrum gradually changes upon heating to 250°C and as a result the absorbance in the range 400-600 nm is increased. That raises the question is it possible to increase the photoinduced birefringence for wavelengths that are far away from the peak of absorbance of the azopolymer PAZO, located approximately at 360 nm. For example, there are powerful lasers at 532 nm, which could be used for optical recording instead of traditionally used lasers in the blue and UV range. To answer this question, we investigated thin film samples of PAZO deposited on quartz substrate and measured continually their spectra of absorbance while heating the samples from room temperature to 250°C. We also measured the photoinduced birefringence using pump laser at 532 nm before and after the thermal procedure. Thus, we report significant increase of the birefringence at 532 nm after the thermal treatment and mention some potential applications.

Direct localized growth of graphene on a substrate: a novel nickel-catalyzed CVD process assisted by H2 plasma.

An original metal catalyzed CVD methodology assisted by hydrogen plasma for the direct deposition of few-layer graphene on a substrate is presented. Graphene is grown at 900 °C directly on the surface of the substrate of technological interest by carbon diffusion through a nickel film by using methane (CH4) as the carbon precursor. Hydrogen atoms in the H2-plasma downstream are used to promote the solubilization of carbon atoms in Ni, thus favouring the growth of graphene at the Ni/substrate interface. Structural and transport properties of the as-grown multilayer graphene films on SiO2/Si and quartz substrates are provided. We demonstrate the peculiarity of this approach for controlling the thickness and transport properties of as-grown graphene films using process-step times. Finally, the potential of the proposed methodology for the bottom-up direct growth of patterned graphene is demonstrated.

Growth and crystal structure of CdTe1−xSex (x ≥ 0.75) thin films prepared by the method of high-frequency magnetron sputtering

CdTe1–xSex (x = 0.75 and 0.95) thin films were deposited on quartz substrate by the method of high-frequency magnetron sputtering. The chemical composition analysis and crystal structure refinement was examined with using X-ray fluorescence spectroscopy and X-ray diffraction data. CdTe1–xSex thin films crystallizes in hexagonal structure [structure type—ZnO, space group P63mc (No. 186)]. Unit cell parameters decrease with increasing Se content in CdTe1–xSex thin films. The value of the optical band gap for CdTe0.25Se0.75 and CdTe0.05Se0.95 was estimating using the Tauc plot and from the maximum position of the first derivative of the transmittance dT/dλ.

Влияние низкотемпературного отжига неупорядоченных плёнок Ge10Se90 на их оптические свойства

In the present paper, the effect of low-temperature annealing on the linear optical properties of disordered thin films (~350 nm) synthesized from Ge10Se90 glass by vacuum thermal evaporation on quartz substrates is reported. Based on the experimental transmission spectra of films in the field of optical transparency before and after annealing below and at the glass transition temperature Tg = (3612) K (313 and 363 K, respectively), the main optical characteristics (dispersion dependences of the refractive index and extinction coefficient, optical gap energy, the Tautz parameter B1/2, etc.) were determined using the Swanepoel and Tautz methods. It is revealed that the edge of optical absorption in the annealed films is caused by indirect optical transitions. Using the Wemple-DiDomenico single oscillator model, the Urbach energy EU, the energy of one oscillator E0, the scattering energy Ed, the linear susceptibility  and the static refractive index n0 were calculated. At the same time, a higher value of the Ed/E0 ratio of the film annealed at Tg indicates its greater nonlinear susceptibility. The X-ray diffraction studies have confirmed the amorphous nature of the initial films and the appearance of Se nanocrystallites in them after annealing of a certain polymorphic modification depending on the temperature and time of annealing. It was found that annealing both below Tg and at Tg initiates red shift in the optical absorption edge, an increase in EU and , and a decrease in the thickness of the film and the parameter B1/2. It is shown that the annealing of identical films is accompanied by a change in their phase composition with the appearance of either monoclinic beta-Se8 nanocrystallites or the mixture of beta-Se8 and trigonal t-Se. From the standpoint of the concept of the polymerpolymorphoid structure of glass and a glass-forming liquid, it is due to the mutual transformation of polymorphoids of various polymorphic modifications because of a change in their concentration ratio depending on the annealing temperature relative to Tg. The resulting films can be used in optoelectronics as nonlinear optical elements or media for radiation limiters.

A self-aligned assembling terahertz metasurface microfluidic sensor for liquid detection.

This paper reports a new terahertz metasurface microfluidic sensor, which is actually a kind of reflective terahertz metasurface absorber with a microfluidic-channel structure located in the strong field energy region of the absorber. The metasurface structure is made on an ultra-thin quartz substrate as the cap layer, while a two-step structure is made on a silicon substrate as the pedestal layer. In order to precisely control the thickness of the microfluidic channel, the cap layer is self-aligned assembled with the pedestal layer to form the terahertz metasurface microfluidic sensor. The obtained sensor could enhance the light-matter interaction, resulting in high sensing performance. The measured results show that the sensor has a perfect absorption peak at 2.60 THz and a high Q-factor of 62.59, which are basically consistent with the simulated results. The sensitivity and FOM calculated based on the measured results of different liquids with different refractive indices is 0.733 THz per RIU and 16.4, respectively. Compared with some recently related work, the sensitivity is increased by about 40%, the Q-factor is increased by 3-5 times, and the FOM is increased by 5 times, which make the sensor have great application potential for solution detection in the terahertz frequency band.

High Performance Thin-Film Lithium Niobate Modulator with Suppressed Slot-Line Mode on Quartz Substrate Fabricated by Photolithography

High Performance Thin-Film Lithium Niobate Modulator with Suppressed Slot-Line Mode on Quartz Substrate Fabricated by Photolithography

Development of thermally stable FTO thin films on quartz substrates for carrier collection in semiconductor photoelectrodes

FTO/quartz prepared by spray pyrolysis maintained both low resistivity and high transmittance at temperatures up to 700 °C, enabling superior photoelectrochemical activity of CuBi2O4 semiconductor photoelectrodes.

Chemically engineered plasmonic Au-gallium oxide nanocomposites for harsh environment applications: an investigation into thermal and chemical robustness.

Enhanced thermal, chemical, and mechanical properties of different metal nanoparticle morphologies integrated with metal oxides have been reported in multiple instances. The chemical and material robustness of metal nanoparticles incorporated surficially and into the bulk of distinct as well as spontaneously formed morphologies of metal oxides through solution-based and microwave-based approaches are investigated in this study. These composites were tested for their chemical and material robustness by exposing films formed on quartz substrates to high temperatures (800 °C) in an air ambient as well as to extreme conditions of pH, often encountered in harsh environment applications such as sensing and catalysis. The changes in the optical properties and crystallinity have been studied using in situ absorption and ex situ X-ray diffraction analyses and electron microscopy. The trends observed with respect to the changes in the plasmonic absorbance were validated theoretically and found to be in reasonable agreement with the experimental data. Confirmations of the phenomena occurring in different morphologies and architectures were thereby corroborated through careful interpretations from experiments and predictions from theoretical models. We, therefore, report a simple solution-based process for achieving engineered harsh environment-compatible nanocomposites through studies specifically tailored for such applications such as catalysis, sensing, energy storage, and enhanced luminescence.

Improved solar cell efficiency of titanium dioxide on porous silicon using pulsed laser deposition at different laser wavelengths

In this study, a Q-switched Nd:YAG laser with specific parameters, including a pulse repetition rate of 6 Hz, a pulse duration of 10 nm, a wavelength of 532 nm, and a laser fluence of 237.47 J cm−12, was employed to fabricate highly crystalline TiO2 nano-films. These nano-films exhibited a narrow energy band gap of 3.24 eV and showcased favorable surface morphology, characterized by a roughness of 2.38 nm. A solar cell device was produced by creating porous silicon (PSi) and applying titanium dioxide films onto the PSi, achieving a notable conversion efficiency of 8.733%. To investigate the impact of different parameters on the resulting TiO2 nano-films, a range of laser fluences (ranging from 131.93 to 263.85 J cm−12) and three distinct laser wavelengths (1064 nm, 532 nm, and 355 nm) were employed during the pulsed laser deposition (PLD) process. These experiments aimed to grow TiO2 films on both quartz and silicon (Si) substrates.

Organic-inorganic PTAA-SiGe transparent optical materials performance analysis for photo device applications

The SiGe materials has currently received a lot of interest due to its application for the advancement of optoelectronics and related sensor technologies. Its promising stability, and band gap-dependent performance for both bulk and nano-crystalline properties are vital as optical materials. To investigate the electrical performance of SiGe active materials based photo device, the spin coated organic p-materials contact is developed on sputtered SiGe on Quartz and ITO glass substrates. Both Si0.8Ge0.2 and Si0.9Ge0.1 films greater than 85 % visible band transparency are predicted that the deposited SiGe is nano-crystalline nature. It is also revealed from absorption-based band gap, AFM grain size and XRD analysis. The transmittance of SiGe thin film is increased with the microstrain of the films as a result, better opto-electrical performance is displayed. Ge composition though slightly makes variation of lattice constant and strain effect however, relatively lower transmittance films greater current density is exhibited. A higher rectifying ratio for lower transparent SiGe material deposited on ITO glass substrate is shown in the dark. Transparency and optoelectrical performance viewpoint white light illuminated PTAA/Si0.8Ge0.2 is shown better on Quartz substrate whereas the dark analysis PTAA/Si0.9Ge0.1 is realized more favorable on ITO glass substrate.

High response hydrogen gas sensor based on palladium coated multi-walled carbon nanotube

H2, which has a zero-carbon footprint, is expected to be one of the main energy sources in the future. The sensitive detection of H2 in the transportation, storage and energy production processes will allow the active use of this resource. Recently, there are many studies in which nanotube-shaped structures are used as high-response gas sensors. In this study, H2 gas response parameters at different temperatures (150, 200 and 250 ºC) of multi-walled carbon nanotube (MWCNT), which were grown on quartz substrate by spin coating method and then Pd coated with DC sputtering, were investigated. The measurements were made at a gas concentration of 1000 ppm with the help of a current-sensitive gas sensor system. The crystallographic structure, elemental content, oxidation levels and surface morphological properties of the produced film were determined by XRS, XPS and SEM analysis. XRD and XPS analyzes support that the MWCNT used in the study is well graphitized and the formation of PdO compound in the structure with Pd coating. The temperature-dependent H2 gas sensing measurements showed that the produced Pd-MWCNT structure had a very high gas response and the highest response was at 200 °C. Comparing the response values obtained with the results of other Pd-CNT structures in the literature, it was determined that the film produced by the economical spin coating method had a very high gas response.

Optimization of structural and electrical properties of graphene-based TiO2 thin film device using Bayesian machine-learning approach

The optimization of laser-induced graphene (LIG) patterning is crucial for achieving desirable electronic properties in flexible electronic devices. In this study, we applied state-of-the-art automated parameter optimization techniques, specifically Bayesian optimization, to enhance the electrical resistance of LIG patterns. By iteratively optimizing the laser power, irradiation time, pressure, and gas type, we achieved minimum LIG resistance within eight batch configurations suggested by the Bayesian optimization (BO) approach. Our method eliminates the reliance on skilled operators, as the initial surrogate models were trained with random parameter evaluations. Notably, our system enables the optimization of material properties even when characterizations are only available outside the experiment loop. Furthermore, the surrogate model provided insights into the underlying mechanisms of LIG growth on quartz substrates. Through partial dependence analysis, we identified relevant physical domains for further investigation, leading to the discovery of negative capacitance and a correlation between structural and electrical properties in LIG. These findings were supported by XPS, Raman, and optical characterizations. Our approach streamlines the experimental design, reducing time and cost while accelerating materials research, and offers human-interpretable conclusions for a deeper understanding of LIG patterning processes.

Electron Irradiation-Induced Degradation of TiN Thin Films on Quartz and Sapphire Substrates.

In this contribution, we investigated the properties of magnetron-sputtered TiN thin films on sapphire and quartz substrates before and after 5 MeV electron irradiation with a fluence of 7 × 1013 e/cm2. Structural, morphological, optical, and electrical properties were analyzed to observe the impact of electron irradiation on the TiN thin films. The results showed improved electrical properties of the TiN thin films due to high-energy electron irradiation, resulting in increased specific conductivity compared to the as-deposited thin films on both sapphire and quartz substrates. The structural features of the TiN thin films on the sapphire substrate transformed from polycrystalline to amorphous, while the TiN thin films deposited on the quartz substrate remained unchanged. Chemical state analysis indicated changes in the metallic bonding between Ti and N in the deposited TiN on the sapphire substrate, while TiN deposited on the quartz substrate retained its Ti-N bonding. This study provides insights into the effects of electron irradiation on TiN thin films, emphasizing the importance of investigating radiation resistance for the reliable operation of optoelectronic devices and photovoltaic systems in extreme ionizing radiation environments.

Employing Electrochemical Potential Cycling to Controlling Surface to Volume Ratio of Nanoporous Gold and Photoelectron Injection into Electrolyte

Nanoporous metals made by alloy corrosion are bicountinuous porous networks that possess nanoscale ligaments and pores and thus a large surface-to-volume ratio. Their ligament and pore size can be tuned between a few nanometers and several microns via thermal annealing [1], which makes them attractive material systems for a variety of applications, including catalysis, sensing, and energy storage. In particular, dealloying-derived nanoporous metals, present novel opportunities for exploring the impact of surfaces on electro-photocatalytic activity of metallic nanostructures [2]. Yet, achieving the ligament and pore sizes in the dealloyed metallic networks below 10 nm, which is especially crucial for understanding an efficient electrochemical charge transfer, is challenging so far.In this study, we demonstrate a successful fabrication of nanoporous gold (npAu) thin films via electrochemical dealloying with the ligament size down below 10 nm on quartz substrate. We study the material by means of in situ photoelectrochemical setup while simultaneously varying the electrode potential in 0.5 M H2SO4 electrolyte. To probe the size effect on the photocurrent response, we exploit cyclic voltammetry (CV) in order to promote coarsening of the ligaments of npAu networks. By varying a number of CV cycles, we were able to induce subtle changes in the ligament size, therefore modifying the surface-to-volume ratio of the nanoporous metals at the lower limit of the nanoscale.Our results show that this approach provides an excellent foundation for future optical investigations of surface effects on the internal quantum efficiency of high-surface area metallic photoelectrodes.Our study demonstrates that modifying the surface-to-volume ratio of the sample by electrochemistry allows us to control the hot electron generation and injection processes in nanoscale plasmonic systems. Moreover, the internal quantum efficiency of the npAu network photoelectrode is significantly influenced by the size of its ligaments. In contrast to prior findings that suggested efficiency would level off with decreasing ligament size [3], we have observed a continuous nonlinear increase in quantum efficiency as the ligament size decreased from 16 to 8 nm. This result is attributed to the increase in absorption by the electrons colliding with the surface (Landau damping) and increase of emission of this electrons into the electrolyte due to possibility of multiple collisions with the surface.